There are several possible reasons why dogs bite their tails, such as allergies and bowel problems. If a dog is continuously biting its tail, it is a often a sign of a bigger problem than an itch.
The most common reason dogs bite their tails is allergies. These allergies can be caused by fleas, diet and other environmental factors according to Vetinfo. The exact causes of allergies are not always identifiable, but there are many types of medication to relieve the symptoms.
Bowel problems are another frequent cause of tail biting. Impacted anal glands can cause biting tails and scooting on the floor. A groomer or veterinary technician can take care of this. Dogs may also bite their tails because constipation or diarrhea is causing bowel discomfort.